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Issue metadata

Status: WontFix
Owner:
Closed: Aug 2017
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Chrome
Pri: 2
Type: Bug-Regression



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Facebook header disappears when modal dialog scrolls above top of page.

Reported by fla...@gmail.com, May 21 2017

Issue description

UserAgent: Mozilla/5.0 (X11; CrOS armv7l 9334.69.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.112 Safari/537.36
Platform: 9334.69.0 (Official Build) stable-channel veyron_minnie

Example URL:
https://www.facebook.com/

Steps to reproduce the problem:
1. On your birthday, go to Facebook just after a few people have messaged you.
2. Click on the "See your birthday posts" link to bring up a modal dialog with posts.
3. Scroll down.

What is the expected behavior?
The facebook header should remain visible in the background.

What went wrong?
If you scroll quickly the header in the background disappears. Sometimes if you scroll very slowly it remains visible.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? N/A 

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 58.0.3029.112  Channel: n/a
OS Version: 9334.69.0
Flash Version: 

I'm able to reproduce on a saved version of the page, so I'll try to minimize it and/or remove personal content. It's likely low DPI specific.
 
actual.png
38.2 KB View Download
expected.png
37.7 KB View Download

Comment 1 by fla...@gmail.com, May 21 2017

It also stopped occurring once there were more posts in my feed and it was no longer the top post so it has something to do with the state when the main scroll is at or near the top.

Comment 2 by fla...@gmail.com, May 21 2017

Confirmed that the problem no longer occurs if I enable device emulation as a laptop with High DPI display.

Comment 3 by flackr@chromium.org, May 23 2017

Components: Internals>Compositing
Labels: Hotlist-ThreadedRendering
Owner: flackr@chromium.org
Status: Assigned (was: Unconfirmed)

Comment 4 by flackr@chromium.org, May 26 2017

Cc: flackr@chromium.org
Components: -Internals>Compositing Blink>Paint
Labels: -Type-Compat Type-Bug-Regression
Owner: wkorman@chromium.org
Looks like this regressed by https://chromium.googlesource.com/chromium/src/+/ccb9e13712b1632b889960d1d85d556c0139fd51. Walter, can you take a look / triage?
Labels: PaintTeamTriaged-20170526 BugSource-Team
Rob: do you have a local repro of this? If so could you reduce it?
I do, I shared a save of the page with Walter, I can share with you too.
I am OOO soon for a few weeks. If this should be looked at before then please find an alternate owner through chrishtr@.
Owner: chrishtr@chromium.org
Owner: flackr@chromium.org
I was unable to reproduce this on Chrome 59 or later based on the testcase
sent to me by flackr@. I also bisected between Chrome 58 and Chrome 59 and could
not reproduce on any of those versions either.

All of the above testing was on a low-DPI linux device, though I also tried
on a Mac w/ Canary and --disable-prefer-compositing-to-lcd-text

Does it reproduce only on ChromeOS for some reason?

@flacker: could you try again to repro? Failing that the bug should be closed..
Status: WontFix (was: Assigned)
Interesting, a reverse bisect pointed me to it being fixed somewhere in this range:
https://chromium.googlesource.com/chromium/src/+log/cd207440f74f112ed24d1e72b63fddbca063dcc9..23449b77810518956542fb0b65be9da863e8492a

Which suggests enabling SlimmingPaintInvalidation fixed it, I'm guessing we ended up disabling this on the 58 branch at some point?

In any event it no longer reproduces on newer versions of Chrome.
Great, thanks.

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